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Abstract

Data on daily milk yield, feed intake as well as simultaneous measurements of daily methane output of 429 first-lactation Nordic Red cows of the MTT research farm was used. Repeatability of different methane phenotypes as well as relationships between feed efficiency (FE) and methane output traits were estimated at different stages of lactation. Cows were divided into divergent FE (high vs.low) groups to ascertain whether cows selected for divergent FE phenotypes also exhibit divergent methane phenotypes. Results showed that relationships between FE and methane output traits varied with stages of lactation. The repeatability of methane phenotypes across lactation stages ranged from 0.1 to 0.7 indicating cow-wise variations suggesting selection for lower methane output could be one mitigation strategy. Divergent FE phenotypes also exhibited divergent methane phenotypes in terms of daily methane output and also per kg of dry matter intake.